This invention relates to window frames which incorporate an integral nailing fin and includes such window frames that also incorporate an integral J-channel to overlap the ends or edges of siding applied around the window opening.
More particularly, the invention is directed to providing a significant saving in the material required to form such window frames and to facilitating their fabrication.
Conventional window frames with integral nailing fins including those with integral J-channels are formed as longitudinal vinyl extrusions having a desired cross sectional profile and a length equal to the length presently deemed required so that it can be cut into four sections for assembly into the window frame to fit into the window opening with the nailing fin circumscribing the window opening.
To provide the required four sections, the profile is cut at angles inclined at forty-five degrees (45xc2x0) to its length from the inner edge of the body portion of the profile out to the outer edge of the nailing fin so that each section comprises a bi-laterally symmetrical trapezoid. These sections are then welded together to provide a rectangular frame having right angled corners including the corners of the nailing fin.
Thus with the present fabricating procedure where the window frame is to provide a square frame opening of 10 inches and the nailing fin is to be 1xc2xd inches wide, the length of the profile required is four times the 10 inches plus eight times the width of the nailing fin or 40 inches plus 12 inches giving a total of 52 inches.
The welding of the abutting 45 degree edges of the abutting frame sections to include the abutting edges of the nailing fins is difficult, particularly as the nailing fins have a degree of flexibility which increases out to the outer edges. Thus, it is difficult to obtain a proper or complete weld out to the very comers of the nailing fins.
Moreover, these welded sharp right angled comers of the projecting flexible nailing fins of the frame are easily damaged in handling.
The present invention resides in cutting the longitudinal window frame profile in a manner to significantly reduce the length of profile material required to form the window frame for a given size of window and window opening.
It will be under stood that as the complexity of the cross sectional configuration of the window frame increases the greater is the saving of material by the ability to reduce the length of profile for a given window size.
Thus, for example, where the window frame includes an integral J-channel, particularly if the J-channel has a complicated formation such a double walled configuration, the saving of material is greatly increased.
More particularly, the invention resides in cutting the length of profile from opposite sides at 45 degrees with the cuts meeting in an intermediate point of the nailing fin so that each of the four sections required to complete the window frame present at each end thereof a right angled triangle having its apex at the intermediate point of the width of the nailing fin. This cutting reduces the length of profile required as compared to conventional cutting by eight times the width of that portion of the nailing fin from such intermediate point to the outer edge of the nailing fin.
Thus, as an example, in the case of the window frame having a frame opening of 10 inches square and a nailing fin having a width of 1xc2xd inches discussed above, if the intermediate point of the nailing fin where the cuts meet is chosen to be the mid-point of the nailing fin the length of profile required to provide the four window frame lengths to complete the frame is four times 10 inches plus eight times xc2xd the width of the nailing fin or xc2xe of an inch. Thus the total length of profile required is only 46 inches as compared to the standard 52 inches.
By providing the window frame sections with the nailing fins having the right angled triangular ends, the sections form when assembled together 45 degree bevelled corners where the abutting surfaces to be welded are only a fraction, e.g. in the example given only one half the length of conventional window frames and there is no welding of any sharp flexible corners as in conventional frames, thus simplifying and facilitating their fabrication.